Separation vessel



United States Patent 3,520,415 SEPARATION VESSEL Lubomyr M. 0. Cymbalisty, Edmonton, Alberta, Canada, assignor of thirty percent each to Cities Service Athabasca, Inc., a corporation of Delaware, Imperial Oil Limited, a corporation of Canada, and Atlantic Richfield Corporation, a corporation of Pennsylvania, and ten percent to Royalite Oil Company, Limited, a corporation of Canada Filed June 17, 1968, Ser. No. 737,577 Int. Cl. B03d N24 US. Cl. 210177 7 Claims ABSTRACT OF THE DISCLOSURE An improved controlled phase separation vessel for separating a hydrocarbon material, specifically bitumen, as a froth from a slurry of water, bitumen and sand is disclosed herein. The vessel has a feed conduit feeding the slurry to a dispersion means consisting of an impeller mechanism mounted in a flood cell, a sand settling zone below the flood cell, and a froth disengaging zone above the flood cell. The froth disengaging zone comprises a froth removal conduit at the vessel top, and an underwash water sparger, preferably a circular transversely mounted tube having a plurality of holes, mounted below the froth withdrawal conduit. A set of turbulence reducing baffles is mounted between the underwash sparger and the froth withdrawal conduit.

This invention is related to an improved apparatus for continuously separating a hydrocarbon material as a froth from a slurry of hydrocarbon material, water, and sand. More particularly this invention is directed to apparatus for efficiently separating bitumen from an aqueous slurry of tar sand.

The economic extraction of hydrocarbon products from either tar sand or shale oil is regarded as the utmost commercial significance. Both tar sand and shale oil represent sources of petroleum products in substantial quantities which due to their location in North America insures a sizeable domestic reserve for future use.

Shale oil deposits in the United States represent 650 billions of barrels of synthetic hydrocarbons while Canadian tar sands represent another 300 billion barrels of synthetic petroleum according to present estimates. One of the most extensive deposits of tar sand occurs for instance in Athabasca District of the province of Alberta, Canada where it extends for many thousands square miles in thicknesses ranging up to more than 200* feet.

The important factor in the economic production of synthetic crude from such resources is the necessity of an economical and effective process for the separation of the hydrocarbon component generally known as bitumen, from the sand or shale materials. Various methods have been proposed for separating bitumen from bituminous sand. Besides those processes which contemplate in situ retorting the two best known methods are often referred respectively to as the hot water method and the cold water method. In the former the bituminous sand is slurried with steam or hot water at about 180 F. and the pulp is then dropped into a turbulent stream of circulated water and carried through a separation vessel maintained at an elevated temperature of about 175 F., so that the oil rises to the top as a froth rich in bitumen. The so called cold water method does not involve heating the bituminous sand other than whatever heating might be required to conduct the operation at a temperature of from about 73 F. to 81 F. The latter process additionally comprises mixing bituminous sand 3,520,415 Patented July 14, 1970 ice with water, soda ash in an organic solvent such as kerosene, and then permitting the mixture to separate at a temperature within about 73 F. to 81 F. Subsequently the bitumen dissolved in the organic solvent rises to the top of settling zone and is recovered.

Many forms of separation apparatus have been either developed or proposed for effectively utilizing the hot water process in an economical manner in order to effectively separate at low cost the bituminous hydrocarbon material from the tar sands. As yet no completely satisfactory process and apparatus have been developed although several are either being tested or as the case of present operations are being used.

I have therefore invented an improved vessel for separating a froth of hydrocarbon material from a slurry of water, hydrocarbon material and sand.

The vessel has a froth disengaging zone which comprises a froth removal conduit at the vessel top and means for continuously feeding water into the froth disengaging zone below the froth removal conduit.

It is therefore an object of this invention to provide an improved apparatus for separating a froth containing hydrocarbon material from a slurry of water-hydrocarbon material and water.

Another object of this invention is to provide an improved controlled phase separation vessel for continuously separating a froth containing bitumen from a slurry of water and tar sand.

Yet another object of this invention is to provide a froth separation vessel having an underwash sparger below the froth interface for separating agglomerates and sand particles from the froth.

Other objects and advantages of this invention will be apparent to those skilled in the art from the brief description of the drawings and preferred embodiment which follow.

In order to more fuly described the apparatus of this invention, drawings of the preferred embodiment are provided, a brief description which is as follows:

FIG. 1 is a cutaway side View of the separation Vessel; and

FIG. 2 is a cutaway isometric view of the disengaging zone of the vessel.

Referring to the drawings wherein the same reference number is used to denote similar components of the apparatus, a separation vessel 12 is shown in schematic form in FIG. 1 of the drawings. The separation vessel is a vertical column shaped shell 14 which is divided functionally into at least three zones, specifically; a mixing zone 16 located about midway in the vessel; a froth disengaging zone 18 located above the mixing zone in the top portion of the vessel; and a sand settling zone 20 located in the bottom portion of the vessel.

In the mixing zone 16, the slurry is subjected to shear by a dispersion mechanism 21 in order to achieve good separation of the oil-water-sand mixture in the slurry and break any clusters or agglomerates. Any clusters or agglomerates in the slurry can either reduce quality of the froth or effective recovery of bitumen. The quality of the froth largely depends on the amount of shear introduced in the slurry during dispersion. Thus the mixing zone 16 comprises an open ended cylindrically shaped flood cell 22 mounted coaxially in the shell 14 at the midpoint thereof, and having the dispersing mechanism 21 centrally located within the flood cell 22. Across each open end of the cell are located turbulence reducing baffies, upper turbulence reducing baffles 24 at the upper end of the flood cell and similar lower turbulence reducing baffles 26 at the bottom end of the flood cell. The turbulence reducing baflles reduce fluid turbulence by introducing linear flow through each open end of the flood cell. Preferably the two sets of turbulence reducing baflles 24 and 26 are constructed of a plurality of vertical plates 28 mounted at parallel spaced intervals to each other and interconnected with a similar plurality of vertical plates 30 mounted in the vertical plane parallel to each other and at right angles to the first plurality of plates 28. Such baflles are generally referred to as straightening vanes and it should be understood that the specifically described boxlike baflle structure is merely one of several structural arrangements capable of performing the function of turbulence reducing. A sample of similarly functional bafl-les are honeycomb or hexagonally shaped battles and those with a tubular cross section or octagonal cross section.

Mounted centrally in the flood cell 22 is a means for feeding wash water and water-tar sand slurry into the mixing zone. This is preferably accomplished by a centrally mounted vertical feed conduit 32 passing through the vessel 12 at its top 34 and extending coaxially downward in the vessel 12 to a point midway in the flood cell 22 and having a feed port 36 located above the dispersion mechanism 21. communicatingly attached to the feed conduit 32 is a flood water feed pipe 38 which passes through the side of the vessel 12 and the flood cell 22 and is communicatingly connected to the feed conduit 32 above the feed port 36.

The dispersing mechanism 21 is mounted in the flood cell below the feed port 36 and acts to impart a washing and shearing action to the aqueous slurry of tar sand impinging upon the mechanism 21. The dispersing mechanism is either a conventional mixer, not shown, or preferably a mechanism having a plurality of rotatable blades 40 vertically mounted on an impeller 42, which is rotatably mounted on a vertical shaft 44 and serves to direct the downwardly flowing slurry outwardly in a radial direction. The shaft 44 is rotatably mounted in a journal 46 and is rotated by means of a mechanical drive, not shown, through a right angle transmission 48 which is securely mounted to the walls of the shell 14. Alternatively the impeller may be rotated by a water turbine drive or equivalent means and thereby dispense with the need for a mechanical transmission assembly for the rotating drive.

Fixedly mounted to the inside wall of the flood cell are a multiplicity of static blades 50 located in the vertical plane adjacent to and surrounding the plurality of rotatable blades 40.

In operation, an aqueous slurry of tar sand is passed into the vessel 12 through the slurry feed conduit 32, and is mixed with flood water if necessary (supplied through water feed pipe 38 from a source not shown). The slurry is passed into the flood cell via the feed port 36 and passes downwardly over the rotating impeller 42 which imparts outward radial flow to the slurry, directing the slurry into the path of the rotating blades 40 and subjecting the slurry to a shearing action between the rotating and the static blades. It is believed that the slurry after being subjected to shear is in a well dispersed state, that is, any agglomerates or clusters of bitumen and sand are broken up. The bitumen and sand are therefore disengaged, and the bitumen particles are attached to small air bubbles. No severe vertical flow patterns however are set up in the flood cell 22 either to carry the heavier sand upwardly or to carry lighter aerated bitumen particles downwardly. The water generally flows away from the dispersion mechanism in either vertical direction and out of the flood 22 through the open ends. A major portion of the sand, being heavier than water, settles downwardly in the flood cell and passes out the bottom end of the flood cell 22 through the lower turbulence reducing baflles 26. The aerated bitumen particles being slightly lighter than the water tend to move upwardly with that portion of the Water passing out through the upper turbulence reducing baflles 24 and out of the flood cell.

A sand settling zone 20 is located in the vessel 12 below the lower turbulence reducing baflles 26. Internally mounted at the lower end of the sand settling zone is an open ended, frusto-conical shaped deflector 58. A second cone shaped deflector 60 is mounted above the open ended deflector 58 in spaced relationship thereto. The two deflectors function in concert to cause the sand-water mixture to change direction radially outwardly thereby causing the sand to move outwardly while the water again changes direction at the bottom of the open ended deflector 48 and passes upwardly inside the open ended deflector and out through the space between the two deflectors.

A middlings removal conduit 62 passes through the outside wall of the separation vessel 12 at an angle so as to slope downwardly into the sand settling zone 20, where the conduit 62 also passes through the wall of the open ended deflector 58 and terminates as a middlings withdrawal port 64 located within the space enclosed by open ended deflector 58. A portion of the water which has reversed direction of flow in the sand settling Zone flows upwardly within the open ended deflector 48 and is withdrawn via the middlings withdrawal port 64 and conduit 62. The upwardly flowing water within the open ended deflector 58 is likely to contain some bitumen particles which are withdrawn together with the water in the middlings stream.

A teeter zone 66 is located below the sand settling zone 20 at the bottom of the separation vessel 12. The teeter zone 66 is formed of an inverted frusto-conical walled cylinder 68 with an upper radial mounting flange 74 which is fixedly attached to the bottom of the shell 14.

Cone valve 76 which is slightly larger than the lower opening 78 of the teeter zone 66 is movably mounted at the opening 78 and can be vertically moved to either close the lower opening 78 or provide an opening of variable cross-sectional area. Means for moving the cone valve comprises a flexible cable 80 having an end fixedly attached to the apex of the cone valve 76. The cable 80 is slidably mounted in a sleeve 84 which in turn is fixedly attached by a pair of support rods 86 to the bottom of the open ended deflector 58. The flexible cable 80 after passing through the vessel wall via an adaptor 88 which permits siding movement while sealing the vessel 12, is attached at its upper end to a clevis joint 90. The clevis joint 90 is pivotly connected to the lower end of a lever arm 92 which is attached by a pin 94 at the fulcrum of the lever arm 92 to one end of a pivot support 96. The other end of the pivot support 96 is attached to the outside of the separation vessel 12. Manual movement of the lever arm 92 will move the cone valve 76 into the desired position either to close the teeter zone opening thereby causing sand to accumulate in the bottom of the teeter zone while the water and middlings continually pass out the middings withdrawal conduit 62 or to open the zone to dump sand.

Extending above the mixing zone 16 and forming a portion of the separation vessel 12 is a quite zone 98. A streamliner 104 is fixedly mounted to the internal wall of the shell 14 and is constructed of a plurality of vertical boxlike baflles similar to the turbulence reducing baflles 24 and 26 mounted in the flood cell 22. These act to streamline the upward flow of water and bitumen particles, reduce turbulence and aid in disengaging any sand carried by the upwardly flowing water.

A recycle conduit 106 communicatingly connected to the shell 14 provides a means for drawing otf water from the shell 14 above the flood cell 22 and recycling the same via a pump 107 to a point in the shell 14 below the flood cell.

A set of turbulence reducing baflles 108 of similar design to the boxlike streamliner 104 is mounted in the upper portion of the quiet zone 98 as shown. Below these turbulence reducing baflles 108 is a set of heating coils 110 which act to heat the upwardly flowing stream if desired. The coils 110 may be of any suitable configuration and may be heated either by hot water, steam or any hot fluid passing therethrough or if desired, even by an electrical heating element.

The froth disengaging zone 18 is located above the quiet zone 98 and is formed of a tubular extension 112 having a somewhat smaller diameter than the shell 14. A connecting flange 114 at the bottom of the tubular extension 112 is utilized for attachment of the disengaging zone to the shell 14. A slightly conical shaped end plate 116 is attached to the top of the tubular extension 112 and forms the top 34 of the separation vessel 12 and has three openings therethrough. Froth withdrawal means is provided and takes the form of a horizontal froth removal conduit 118 which is attached to one of the openings in the end plate 116 and form together with the opening a froth removal port 120. A second axially located sealed opening has the slurry feed conduit 32 passing therethrough. The third opening in the end plate 116 has a smaller diameter water underwash feed pipe 122 passing therethrough.

The underwash feed pipe 122 extends downwardly to the bottom of the froth disengaging zone 18 where it is communicatingly connected to a transversely mounted circular underwash sparger 124 having a multiplicity of holes 126 through which underwash feed water is passed into the bottom of the froth disengaging zone 18.

Mounted above the underwash sparger 124 is another set of turbulence reducing baffles 128 of similar design to the baffles described above, which serve to reduce turbulence below the froth-water interface 130. The froth water interface is established and maintained in the operation at a level just below the froth withdrawal port 120.

In operation the slurry of water, bitumen and sand is fed through the slurry feed conduit 32 to the mixing zone 16 just above the dispersing mechanism 21 and mixed if necessary with water added from the flood water feed pipe 38. The dispersing mechanism 21 which is preferably of the type described herein, serves to disperse and shear the slurry, aerate the bitument particles and separate the sand and bitument particles. A major portion of the bitumen particles being lighter than water tend to rise out of the flood cell 22 together with the upwardly flowing portion of the water and pass through the upper turbulence reducing baflies 24 at the upper end of the flood cell 22, then through the quiet zone streamliner 104, upwardly past the heating coils 110, and past the underwash sparger 124 to the top level of the water where the bitumen forms a froth floating on top of the water. Utilizing underwashing displaces solids and froth particles associated with coarse solids and aids in preventing entrainment of fines in the recovered emulsion or froth. In addition the amount of Water required in froth separation is reduced. Froth is continually removed through the froth removal conduit 118 and passed for subsequent treatment such as dewatering to obtain a synthetic hydrocarbon petroleum oil.

Having described the apparatus of this invention and wishing to cover those changes and modifications which 6 are apparent to those skilled in the art without departing in any way from the spirit and scope of this invention,

I claim:

1 A vessel for continuously separating a froth of hydrocarbon material from a slurry of Water, hydrocarbon material and sand, said vessel comprising slurry feed means, slurry dispersion means positioned in an intermediate portion of the vessel, sand settling means positioned below said dispersion means, froth withdrawal means positioned above said dispersion means to form a disengaging zone, means for feeding underwash water into the froth disengaging zone below the froth withdrawal means, said underwash water feed means comprising a circular tube transversely mounted below the froth withdrawal means, said tube having a plurality of holes through which water from said tube passes out to the froth disengaging zone, means for feeding water into the tube and turbulence reducing bafiies mounted above and below said tube.

2. The apparatus of claim 1 which additionally comprises heating means mounted in the froth disengaging zone below said transversely mounted tube.

3. The apparatus of claim 2 wherein said heating means is a set of heating coils positioned below said turbulence reducing baffies mounted below said tube.

4. A vessel for continuously separating a froth of hydrocarbon material from a slurry of water, hydrocarbon material and sand, said vessel comprising slurry feed means, slurry dispersion means positioned in an intermediate portion of the vessel, sand settling means positioned below said dispersion means, froth withdrawal means positioned above said dispersion means to form a froth disengaging zone, means for feeding underwash water into the froth disengaging zone below the froth withdrawal means, and turbulence reducing baflles mounted above and below said means for feeding underwash water into the froth disengaging zone.

5. The apparatus of claim 4 wherein said means for feeding underwash water into the froth disengaging zone comprises a circular tube transversely mounted in the froth disengaging zone below said froth withdrawal means, said tube having a plurality of holes from which water from the tube passes into the froth disengaging zone, and means for feeding water into the tube.

6. The apparatus of claim 4 which additionally comprises heating means mounted in the froth disengaging zone below said means for feeding underwash water into the froth disengaging zone.

7. The apparatus of claim 6 wherein said heating means is a set of heating coils.

References Cited UNITED STATES PATENTS 3,298,519 1/1967 Hollingsworth 209-170 X J. L. DE CESARE, Primary Examiner US. Cl. X.R. 210-221 

